Lock



LOCK

Filed Uan. 12, 1928 Patented Apr, 2, .129,

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LOCK. i

Application led January 12, 1928, Serial No. 246,205, and in Great Britain tovember 25, 1927.

yI his invention relates to locks of the type known as cylinder locks in which pin tumblers are employed which enter the plug and prevent its rotation until the pins are moved '5 to an inoperative position by the insertion of a ke Devices have been proposed which i enab e this type of cylinder lock to be opened,

type referred to, and according to the invenv tion means are provided for detecting and preventing the unauthorized opening or cylinder locks consisting in the provision of ad-'- ditional movable pins adapted, on insertion of an unauthorized key, to engage such key `or the rotary plug or barrel to prevent complete movement of the movable elements for the opening of the lock.

ln carrying the invention into eect,a lock casing is provided with one or more sliding ziiungers disposedradially relatively to the plug and ada ted to engage in one or more of the pin tum ler sockets to prevent further movement .when an attempt is made to rotate the plug with an unauthorized key.

Reference will now be made to the accompanying drawings which illustrate, by way of example, a construction according to the invention and in which lFigure l is a longitudinal sectional 'view of a lock provided with means for preventing operative rotation by an unauthorized key.

Figure 2 is a cross section on the line 2-2 or@ Fi ure 1.

Re erring to the drawings the locking means take the form of plungers or auxiliary pin tumblers 8 slidably mounted in sockets 9 extending through the iixed cylinder or casing 19 of the lock at an angle to the sockets 11 in which the upper and lower pin tumblers 12 and 13' are housed. rllhe plungers 8 are held in engagement with the periphery of the rotary barrel or plug 14: by sprlngs 15, and the outer ends of the sockets 9 are closed'by grub screws 16 which are inaccessible when the lock is operatively mountedon a door, window or the like. rihe lug 14' is provided with the usual key slot l? on either side of which a'plunger 8 is arranged so as to prevents turning of the plug ineither direction should an unauthorized key be inserted.v At least two plungers 8 are thus employed, but others f may be disposed at or near the rearl portion of the plug 14:.`

It is preferred to form the plunger 8 with a portion of reduced diameter as shown at.

18, and adjacent this portion is disposed an auxiliary locking plunger 19 disposed yin a socket 20 extending 1n a direction parallel to the axis of the plug 14 and accessible from the rear of the casing 10 where'it is closed by a grub screw 21 between which and the plunger 19 is disposed a' coiled spring 22.

In the operation of the lock shown, an unauthorized key can be inserted and used to ar the tumbler pins 12 and 13 out of engagement with the plug 14 but as an unauthorized key, such as 23, will not maintain all of the'- lower pins 13 with their heads flush with the periphery of the plug 14, at least one of the plungers 8, under the action of its spring 15, will enter one of the sockets for the pins 13' when the glug 14 has made a short partial rotation an prevent further movement thereof so that the device as a whole is locked absolutely, even against the insertion of the s correct key. ln this manner, any attempt to tamper with a lock can subsequently be detected by the person holding the correct key. The plungers 19 constitute an additional safeguard to prevent the locking plungers 8 from being jarred outwardl by tapping the key, as movement of one ci the plungers 8 towards locking position brings the recessed portion 18 into the path of the locking 'plunger 19 which immediately engages in the recess 18 under the influence of its spring, so that the locking plungers are themselves locked in operative position. By duplicating this arrangement on either side of the pin tumblers 12 and 13 locking ot the parts against operation occurs in either of the two directions in which the plug 14 can be turned.

It is to be noted that the correct key for any particular lock will bring all the pins 13 into a position in which their outer ends are maintained flush with vthe surface of the plug 14 so that they pass the plungers 8 without affording the latter any opportunity for inward and locking movement.

rIhe invention possesses the further advantage that it can, without diiiioulty, and at small cost, be applied to any existing lock of the pin-tumbler type.

ll claim 1u A pin tumbler lock including a casing, a key plug provided with a key slot mounted for rotation in the casing, a plurality of main pin tumblers mounted in the casing for holding the key plug from rotation, two auX- iliary pin tumblers one upon each side of the roW of main pin tumblers for coaction with the key plug to limit the rotation of the key plug in either direction and to be released only by a key formed to properly release all of the main pin tumbl'ers, and an auxiliarly locking plunger for each auxiliary pin tumbler mounted in the casing.

2. A pin tumbler lock including a casing, a key'plug provided with a key slot mounted for rotation in the casing, a plurality of main pin tumblers mounted in the casing for holding the key plug from rotation, two auxiliary pin tumblers one upon each side of the row of main pin tumblersfo'r coaction with the key plug to limit the rotation of the key plug in eitherdirection and to be released only by a key formed to properly release'all of the main in tumblers, said auxiliary pin tum.- blers eing spring projected, and an auxiliary locking plunger for each auxiliary pin tumbler mounted in the casing.

In witness whereof ll aflix my signature.

LEONARD PEPPER. 

